Lectrical means for indicating at alpha distance the motion of an apparatus



Feb. 9 1926. 1,571,960

J. c. NEEDHAM ELECTRICAL MEANS FOR INDICATING AT A DISTANCE THE MOTION OF AN APPARATUS Filed Nov. 1920 2 Sheets-Sheet 1 IHHIHIJI IIHHIIH W: 3; AHE ASFBRN flllllfil J. c. NEEDHAM ELECTRICAL MEANS FOR INDICATING AT A DISTANCE THE MOTION OF AN APPARATUS Filed Nov. 17, 1920 2 Sheets-Sheet 2 A T'X Patented Feb. 9., 1926.

UNITED STATES PATENT OFFICE.

JonN OUTHBEBT NEEDHAM,

OF CHISWICK, LONDON, ENGLAND, ASSIGNOB TO 11m- SELF AND EVEBSHED & VIGNOLES, LIMITED, F CHISWICK, LONDON, ENGLAND, A COMPANY OF GREAT BRITAIN AND IRELAND.

ELECTRICAL m ANs FOR INDICATING AT A DISTANCE THE MOTION or AN APPARATUS.

Application filed November 17, 1920. Serial No. 424,576.

To all .whom it may concern:

Be it knownthat JOHN CUTHBERT Nano- HAM, subject of the King of Great Britain and Ireland, residing at Acton Lane Works,

Chiswick, London, W'ri, England, has invented new and useful Imsgroved Electrical Means for Indicating at a istance the M0- tion of an Apparatus, of which the following is a specification.

This invention has for its object the construction of electrical apparatus for indicating at a distance whether a mechanism is in mot-ion, and if so, in which of two d1- rections. i A commutator is arranged so that when it is rotated it makes a succession of contacts, alternately charging a condenser from a source of continuous electric current and discharging it through a current-indicating device, the succession of contacts being so arranged that when the moving art of sa d commutator is rotated in one irection the discharge from the condenser flows through the indicating device in ,a specified direction and when the direction of rotation is reversed the direction of flow of the discharge current through the indicating device is reversed. The indicating'device is olarized so that it deflects to one side or t e other, or. rotates in one or the other direction, according to the direction in which the condenser discharges through it, and therefore accordingto the direction of rotation of the commutator; while it remains at a central zero (or if a rotating device, remains motionless) if the motion of the commutator stops.' The amount of deflection (or the speed of rotation ,if the current mdlcatmg device is of a rotatory character) depends upon the capacity of the condenser, the charging pressure and the speed; all these can be admst'ed so that full scale deflection is obtained (or a rotation at a reasonable s produced in the indicator) for quite s ow motions of the mechanism with regard to which information is required. If the polarized current indicating device is of the typ: us' rpermanent magnets, reversal of t sup y voltage Wlll reverse the indications of t etinstrument. To overcome this objection 'electro-magnets en- -ergiudfromthesamesmirceof supply as thatu'sedwcharpthecondensermaybe used. The energizing of the magnet of the current indicating device necessitates the runnlng, of two extra conductors to the receiving position, but by the provision at the transmitter and receiver of a contact at a potential intermediate and preferably about mld-way between that of the positive and negative terminals of the supply I am able, 1n the case of apparatus employin the discharge current to eliminate one 0% the connectionsbetween the transmitter and the actuating coil of the current indicator.

Referring to the drawings Figs. 1, 2, 3 and 4 show typical arrangements of this apparatus employing the discharge current and Fig. l 'is a sectional view of the commute-ting device employed In these arrangements. I therefor do not in any way limit myself to the arrangements llustrated, as it is obvious from the nature of the invention that the arrangements of the connections and apparatus maybe varied n many ways to suit various requirements. Fig. 1 illustrates the system in 1ts simplest fornn A condenser a is connected to the shp rings d, d a source of electric supply is connected to contacts e, e, and an indicating instrument to contacts a, 0', these contacts being so mounted on a brush arm I: rotated by that, the motion of which is to be observed, successively connect the condenser to the supply andto the instrument.

a are provided to prevent short circuiting.

Blank contacts disposed that brushes 1), b,

The indicating instrument shown is a centre-zero spring-controlled galvanometer comprising a permanent magnet f, a moving coil g, a spring g, ainter h, and dial h which may be marke to suit r uirements. The direction of the current through the indicator de nds on the direction of rotation of the rush arm k. In the arrangement I have shown, clockwise rotation of k causes the discharge current to be positive at a and negative at c, and obviously if the apparatus is revolved in an anti-clockwise direction 0 will become negative and a positive. If the brush arm stops rotating, no deflection occurs on the instrument after the condenser has lost its cha It will be noted that the contacts must brushes cannot simulso spaced that the taneously bridge two adjacent contacts, as

ischarging otherwise there is a liability of the engine stopping with the brushes bridging a charging an dischargin osition which would cause a permanent ediaction to be shown at the indicating instrument. -When the brush arm is rotating .in a clock wise direction the condenser is charged from the positive of supply through the bush 6, brush conductor k, slip ring (I to condenser a; from condenser a throu h slip ring d, brush conductor kflbrush to negative'of supply, and discharged throu h slip ring d, brush con ductor k, brush g and contact 0 to conductor a through coil 9 and conductor a to contact a, and through brush conductor in and slip ring (2' back to condenser a from the above the charging and discharging circuits may be readily traced when the rotation of the brush arm is in a counter clock wise direction.

Fig. 2 is similar to Fig. '1 as regards the transmitting unit but the field magnet of the indicator is no longer a permanent one. Itis wound with magnetizing coils m and mwhich are energized from the same source of supply as the system. This system is preferable to that shown in Fig. 1 as a reversal of the polarity of the supply will not affect the readings of the indicator.

Fig. 3 is somewhat similar to Fig. 2 but in order to economize wiring, the conductor cis omitted and resistances r, 'r' are inserted in the transmitter and connected to the contact 0 by a conductor 7", a second resistance is also provided, said second resistance conveniently being the field magnet windin m, m of the indicator, which is connec to the coil {1 thereof by a conductor g It is essentia with this arrangement that the potential of the conductor 1 is equal to the potential of the conductor 9' so as to form a convenient discharge circuit for the condenser a through coil 9.

Fig. 4 is a similar system to that shown in Flg. 3 as regards the method of connection, but in this case the indicator takes the form of a small motor 25, the pointer h being attached to the armature shaft and rotating in either direction in accordance with the direction of rotation of the transmitter.

I claim 1. Electrical means for indicating at a distance whether a mechanism is in motion and if so in which oi two directions, comprising, in combination, a source of continuous electric current, an electrical condenser, a polarized indicator and commutating means operated by the mechanism under observation for alternately connecting said condenser with said source to charge said condenser in a direction dependent upon,

the direction of rotation of said commutator and connecting said condenser with said indicator so that said condenser can discharge through said indicator.

2. Electrical means for indicating at a distance whether a mechanism is in motion and if so in which of two directions, comprising, in combination, a source of continuous electric current, an electrical condenser, a polarized indicator the direction of rotation of which is dependent u on the direction of flow of electric current t rough its moving part, and commutating means operated by the mechanism under observation for alternately connecting said condenser with said source to charge said condenser in a direction dependent upon the direction of rotation of said commutator and connecting said condenser with said indicator so that said condenser can discharge through said indicator.

3. Electrical means for indicating at a distance whether a mechanism is in motion and if so in which of two directions, comprising, in combination, a source of continuous electric current, an electrical condenserf a polarized indicator the magnetic field 0 which is induced by coils directly connected to the source of supply, and commutating.

means operated by t e mechanism under observation for alternately connecting said condenser with saidsource to charge said condenser in a direction dependent upon the direction of rotation of said commutator and connecting said condenser with said indicator so that said condenser can discharge through said indicator.

In testimony whereof I have signed my name to this specification.

JOHN CUTHBERT NEEDHAM. 

